Field of the Invention
The present invention relates generally to an orifice probe apparatus, and more particularly, to a rectal probe apparatus for use in diagnostic procedures as well as methods for the use of such probes probe apparatus.
Description of the Prior Art
As an extension of the brain, the nerve roots send and receive messages to and from the pelvic organs and lower limbs. FIG. 1 shows an approximate top view of a vertebra with the cauda equina (a bundle of nerves that extends from the base of the spinal cord through the central spinal canal) shown in cross section and two nerve roots exiting the central spinal canal and extending through intervertebral foramina on either side of the vertebra. The spinal cord and cauda equina run vertically along the spine through the central spinal canal, while nerve roots branch off of the spinal cord and cauda equina between adjacent vertebrae and extend through the intervertebral foramina.
Cauda equina syndrome is a condition in which there is severe neural compression of the lumbar or lumbosacral spine such that the sacral roots become non-functional and the patient loses control of the bowel and bladder. Other manifestations of cauda equina syndrome can include saddle anesthesia or radiating pain down the lower extremities with associated weakness or numbness. However, the hallmark of cauda equina syndrome is severe neural compression below the conus causing frank loss of bowel and bladder control. This can manifest itself either with urinary retention and inability to urinate with severe pain from bladder expansion, or frank loss of bowel and bladder control causing the patient to either urinate or defecate on himself or herself without realizing that this has occurred. The fact that saddle anesthesia is often present would also cause the patient to not realize that such an accident had happened.
Lower back pain is common and usually resolves with non-operative care. When stenosis, or nerve compression, is present however the patient will often experience severe pain radiating into the lower extremities following the distribution of the nerves being compressed. The patient may also experience weakness, numbness, and/or tingling with difficulty walking or standing. Surgical management in the form of a decompression to take the pressure off of the nerves that are being compressed or crushed may be required in these cases to alleviate the patient's neurogenic symptoms.
Despite this, however, even cases of stenosis, or nerve compression, are not true surgical emergencies. In general there is not felt to be a rush for surgery and the appropriate time to treat neural compression in the lumbar spine surgically is when the patient's quality of life has reached a point where it is unacceptable and when all reasonable non-operative treatments have failed. If surgery is performed to decompress the lumbar neural elements the success rates are excellent, in the 85-90% range for improvement of neurogenic symptoms. It is not until the condition has been present for over two years that a decline in success rates was noted and even in these cases the decline is only by approximately 10%. Thus, if the condition has been present for over two years, the success rates would still be in the 75-80% range. As such, patients are typically advised that surgery for stenosis is a “quality of life” issue that the patient considers when he or she is ready and wishes to proceed.
However, the one lumbar condition that would be considered a surgical emergency is cauda equina syndrome. Cauda equina syndrome is relatively rare, encompassing less than 1-2% of cases of stenosis. However, when present, this is a true surgical emergency, and surgery that is not performed on an emergent basis has been found to lead to a dramatic decrease in success rates and postoperative function. Because regaining the ability to control one's bowel and bladder is universally accepted as being very important, surgery is recommended to give the patient the best chance of regaining this important function. A recent study by Ahn et al., Spine, 1999, demonstrated that if decompression surgery was performed within 48 hours, that this affords the patient the best chance of improvement of return of bowel and bladder control in the 80% range. If one waits beyond 48 hours to perform the decompression, the success rates fall to approximately 50-60%. {Ahn, U. M., Ahn, N. U., Buchowski, J. M., Garrett, E. S., Sieber, A. N., Kostuik J. P., “Cauda equina syndrome secondary to lumbar disk herniation: a meta-analysis of surgical outcomes,” Spine (Phila., Pa., 1976). 2000 Jun. 15; 25(12):1515-22.} Thus, cauda equina syndrome is considered a true surgical emergency.
The causes of cauda equina syndrome can include, but are not limited to, a massive herniated disk, severe spinal stenosis, spondylolisthesis, or any mass such as a tumor or infection causing severe nerve compression. However, regardless of the cause, the common thread is that there is severe nerve compression below the conus causing the sacral roots to shut down with loss of bowel and bladder control.
The most common cause of cauda equina syndrome is a lumbar disk herniation causing excessive compression on the cauda equina. Cauda equina syndrome is relatively uncommon with an incidence of approximately 1-2% of all herniated lumbar disks. The results of cauda equina syndrome are often very serious, being both painful and having many debilitating effects. These include life-sustaining disabilities including bowel and bladder incontinence, leg weakness, gait abnormality, painful paresthesias, urinary retention, genito-urinary deficits, including numbness in the buttocks, the vagina (of a woman), neurogenic bladder dysfunction, neuropathic pain, which can be paralyzing, sexual dysfunction and inability (of a woman) to have children. Although cauda equina syndrome is an uncommon occurrence, this condition can be encountered by any physician since lumbar spinal stenosis and lumbar disk herniations are very common.
Because this is considered an emergent situation, a great number of lawsuits have arisen due to “missed” cauda equina syndrome. As noted above, even though stenosis or nerve compression is present, cauda equina syndrome is only present if there is a loss of functioning of the bowel and bladder. The hallmark of determining if an individual has cauda equina syndrome, however, is not based on the patient's subjective complaints but rather on a rectal examination. Typically, the clinician will insert a gloved finger into the anus and subjectively measure tone, volition and perianal sensation. However these are subjective measurements and there is no objective measure as to what normal tone and volition would be. In addition, based on the clinician's experience, different opinions can be generated. Furthermore, because cauda equina syndrome is relatively rare, many clinicians may not have experience with a truly abnormal rectal exam in which the tone is diminished or absent. For example, even if the patient has minimal or no anal tone, the patient can press the gluteal muscles together giving the appearance that tone or volition is present when it really is not.
Perianal or rectal sensation may also be measured by the clinician by applying a stimulus or stimuli to the perianal or rectal area of the patient, for example, pinprick from a safety pin applied to the perianal area on both the patient's right and left sides. A reduced or lack of sensation reported by the patient in response to the perianal pinprick indicates to the clinician that the patient may be at risk of cauda equina syndrome. Perianal sensation is often difficult to test. Patients are in pain and are usually very uncooperative. Moreover, the patient has to be rolled over in order to make the patient's anus accessible. Without the cooperation of the patient, it is difficult to position the patient properly. Some patients are unable to express as to whether or not they have reduced or no perianal sensation, such as patients who are suffering from dementia. Therefore, perianal sensation is oftentimes not measured. This is problematic because the hallmark of determining if neurologic function is present includes both motor and a sensory examination. Further, the conventional perianal sensory pinprick tests also suffer from a variety of deficiencies. Such deficiencies include, but are not limited to, difficulty in accessing the perianal area with a safety pin and applying the appropriate force when pricking the perianal area with the safety pin.
Thus, cauda equina syndrome is a relatively uncommon condition. It is usually associated with a large, space-occupying lesion within the canal of the lumbosacral spine. As noted above, cauda equina syndrome can be characterized by low back pain, sciatica, lower extremity sensory motor loss and bowel and bladder dysfunction, but it is the loss of bowel and bladder function that defines this condition and separates it as a true surgical emergency.
The initial signs and symptoms of cauda equina syndrome can be subtle, and include saddle anesthesia of the perineum, urinary retention, numbness, bilateral lower extremity pain and weakness. Cauda equina syndrome is often overlooked since a great many patients under primary and emergency care of physicians have low back pain and sciatica and since cauda equina syndrome is rare. Due to the great frequency of lumbar disorders, and overall rarity of cauda equina syndrome, it is common for clinicians to overlook this condition.
Although cauda equina syndrome accounts for a small minority of cases of lumbar disease, therefore, the overall frequency of lumbar disorders in general means that this condition does occur with reasonable frequency and may be encountered by any physician. Thus, cauda equina syndrome is considered a condition in which every physician should be familiar and also one in which is it considered unacceptable practice if it is missed. It is considered below the standard of care for any physician to miss this condition and delay the emergent surgical treatment for this problem.
Due to these and other deficiencies of such conventional screening techniques and the severity of the outcome if improperly diagnosed, physicians routinely rely on MRI (magnetic resonance imaging) scans or CT myelograms (in patients who cannot undergo MRI) to rule out this condition by ruling out severe neural compression. However, cauda equina syndrome is rare and such procedures are expensive and cumbersome, particularly when ordered after hours in an emergency room situation. Due to the perceived rarity of cauda equina syndrome, there has been no practical probe developed for routine examination for cauda equina syndrome, resulting in missing the occurrence of this syndrome. When a missed cauda equina syndrome does occur, and surgical management is delayed, the success rates for recovery of bowel and bladder dysfunction are significantly diminished. This in turn may result in unfortunate and expensive treatments, as well as huge awards from medical malpractice lawsuits.
Cauda equina syndrome is considered a surgical emergency of which every physician is expected to be aware. The inventor performed a preliminary review of seven cases decided in the U.S. courts related to cauda equina syndrome. The cases reviewed are the following: Rutledge & Rutledge v USA, Civil Case #06-00008, 2008 W, 2008 WL 3914965 (D. Guam 2008); William Owen v USA, Civil Case #07-4014-KES, 2008 WL 5122282 (D. S.D. 2008); Dollard v Allen, Whip, LVMC, Civil Case #02-CV-87-B, 2005 WL 2007028; Jimerson v USA, Civil Case #99-CV-0954E(Sr), 30 ILR 3164 (N.D. N.Y. 2003; Kling & Kling v Disclafani et. al., Case No. 5D07-2019, (Fl. Dist. Ct. App. 2008); Skrzypchak & Skrzypchak v Paul Jensen et. al., Appeal Nos. 2007AP2729, 2008AP154, (Wi. Ct. App. 2009); and Stitt v Dept. of Corrections State of Georgia et. al. (250 Ga. App. 420, 551 S.E.2d 793 (2001)). Of these seven cases, four resulted in a verdict for the plaintiff, with judgements ranging from $500,000.00 to $7,502,674.00. Thus, the huge settlements in these cases highlights the importance of being able to determine the presence of cauda equina syndrome not only to give the patient the best chance of recovery of bowel and bladder control but also to protect the provider and institution from possible legal ramifications.
A study of these cases demonstrated that time to diagnosis and surgery ranged from under 24 hours to over one month, and did not predict which cases would rule for the plaintiff. Severity of initial symptoms also did not predict which cases would rule for the plaintiff. The one common thread in all cases in which a judgement was ruled for the plaintiff was that no rectal examination was performed by the treating providers. This was consistently considered a significant factor in determining failure to provide the standard of care.
As noted previously, a study by Ahn et. al [“Cauda equina syndrome secondary to lumbar disc herniation: a meta-analysis of surgical outcomes,” Ahn U M, Ahn N U, Buchowski J M, Garrett E S, Sieber A N, Kostuik J P, Spine (Phila Pa. 1976). 2000 Jun. 15; 25(12):1515-22.] demonstrated that, if surgery is performed within 48 hours of onset of cauda equina syndrome, the success rates for return of bowel and bladder control are significantly higher than if surgery was performed after 48 hours. This study also demonstrated that for all cases performed within 48 hours there was no difference in success rates, and that for all cases performed after 48 hours there was no difference in success rates. Scientifically, therefore, time to surgery has been the only factor which has been shown to influence outcomes for patients with cauda equina syndrome. Nevertheless, time to surgery weighed very little on the verdicts which were handed down. It was the lack of an adequate rectal examination which appeared to carry the most weight in determining guilt in these cases.
In the case of Rutledge & Rutledge v USA, Civil Case #06-00008, 2008 WL 3914966 (D. Guam 2008), in which a judgment for the plaintiff of $7,502,674 was granted, the defendant successfully sued the VA Medical System (and thus the U.S. government) even though the claimant only complained of back pain and vague vaginal symptoms on initial presentation. The claimant did not complain of any bowel or bladder changes, nor did the claimant complain of true saddle anesthesia or lower extremity symptoms that would make the clinician suspicious for cauda equina syndrome. Thus, the defendant did not have any of the typical signs or symptoms of cauda equina syndrome and certainly did not have a loss of bowel or bladder control on initial presentation. It was not until 30 days later that she actually presented with true loss of bladder control, and at that point imaging studies were performed emergently and surgery was performed within 24 hours. Despite the fact that the claimant appeared to have received adequate care, the fact that a rectal examination was not performed on initial presentation, even though the symptoms were atypical for cauda equina syndrome, made a huge impact on the overall outcome of the case with an enormous penalty attributed to the treating providers for not having checked rectal tone. This highlights the importance of a good rectal exam in treating any patient with lumbar symptoms. A knowledge of cauda equina syndrome and that this condition is an emergency is expected of all providers.
However, cauda equina syndrome is also very rare, and even the busy spinal surgeon will only see one or two cases per year. This calls into question the legitimacy of the rectal examination particularly when performed by a clinician who has not seen patients with this condition and is not familiar with spinal disorders. This is a primary impediment to performing an adequate rectal examination that was frequently cited in these cases; that the treating provider was not a specialist and would not know if the rectal exam was truly abnormal or not. That said, this proved to be an inadequate defense in these cases.
Having a device designed to specifically rule out cauda equina syndrome would therefore be invaluable to the treating provider as well as to the institution at which the provider works as it would allow for an adequate defense should a patient argue that the presence of cauda equina syndrome was “missed”. Furthermore, having a device which would objectively give a value to definitively determine if the rectal tone is within normal limits or concerning would allow the clinician to freely discharge certain patients with follow up while still protecting the provider and the institution from potential claims.
It is not reasonable for the treating provider to consult a spinal surgeon for every single patient with lumbar complaints, as back pain is second only to upper respiratory infections for reasons that patients see their primary care physicians. It is also not reasonable from a cost perspective to order an MRI on every patient with lumbar complaints. A simple inexpensive device to rule out this potentially devastating condition is thus necessary and not currently available.
Therefore, it would be desirable to provide a probe and accessories wed with the probe (referred to as “probe apparatus”) and a method of using the probe to diagnose cauda equina syndrome. Having a probe apparatus which would allow an objective measure of normal anal/rectal tone would be of great benefit in providing medical diagnosis in a patient with low back pain or neurogenic symptoms in terms of ruling out cauda equina syndrome, particularly in an emergency room environment. Furthermore, having a probe apparatus that would allow for a definitive sensory evaluation to be performed would also be of great benefit. Such probes probe apparatus would be considered more sanitary, both for the clinician as well as for the patient and would provide more of an objective measure to provide a more definitive method of assuring that this devastating condition is not present for the patient. It would be especially beneficial if such probe apparatus could be developed which is relatively inexpensive to manufacture, is disposable after use, and is reliable in detecting cauda equina syndrome.
Cauda equina syndrome also occurs in animals, and especially in dogs, particularly dachshunds. Because dachshunds are afflicted with the same genetic disorder causing Achondroplasia in humans, they are subject to same severe spinal stenosis that Achondroplasts typically suffer from due to a congenitally small spinal canal when middle-adulthood is reached. The most common symptom is pain, particularly pain in the back, on one or both hind legs, or tail; however, because an animal cannot report symptoms it is frequently difficult to determine if the stenosis has become severe. The condition usually progresses until the dog has become completely incontinent and has lost function in the lower extremities; specialized wheel-walkers for dachshunds have been manufactured because lower extremity paralysis occurs so frequently in these dogs. Currently, diagnoses are made by checking the reflexes, a neurological exam and performing a myelogram (i.e., injecting dye and performing plain films). However, it is difficult to perform a neurologic examination in a dog that cannot follow commands, and reflexes have poor sensitivity and specificity in determining if severe stenosis is present. Furthermore, myelography is painful, has associated risks, and is expensive and invasive and as such is a poor tool for routine screening. Although it would alert the owner and veterinarian that impending or significant neurologic compromise is occurring, an anal exam is not typically performed on a routine basis in these dogs, even when they have reached an age where severe stenosis and loss of neurologic function is common. Since the invention disclosed herein can be used both on humans and on animals, the term “patient” as used herein applies both to humans and animals.
It should also be noted that extrinsic compression occurring at the conus medullaris or the spinal cord itself can also cause changes in, or a loss of bowel and/or bladder function. Thus, while compression of the cauda equina is the most frequent cause of loss of bowel and/or bladder function occurring from extrinsic neural compression, the physician must also be aware that compression higher in the neural axis can also lead to alterations in bowel and/or bladder function as well. For the purposes of this application, any condition in which extrinsic neural compression leads to an alteration in bowel or bladder function, such as cauda equina syndrome, conus medullaris syndrome, or spinal cord compression will be termed “cauda equina syndrome.”
A health problem which many physicians must be aware of is the enlargement and changes in the normal shape of a man's prostate gland which may be an indication of urinary symptoms and prostate cancer. The first examination, which is usually the first test done, is the digital rectal examination. In this examination, the doctor inserts a gloved finger into the rectum and feels the part of the prostate next to the rectum. This examination gives the doctor a general idea of the size and condition of the gland. This is a subjective test, and depending on the person applying the test, indicates its accuracy. Although it is usually just an initial test to determine whether further tests should be made, the skipping of the test or a misjudgment of the test results could lead to dire consequences. If there is a suspicion that prostate cancer has occurred, a probe can be inserted into the rectum for directing sound waves at the prostate. The echo patterns of the sound waves form an image of the prostate gland on the display screen indicating whether or not a tumor may be present. If a tumor is suspected, a biopsy is usually used to remove prostate tissue for examination under a microscope. This same condition could apply to males of many animals.
A number of devices have been developed for measuring specialized muscle function. In U.S. Pat. No. 5,452,719 (Eisman et al., 1995), an electrode is discussed for providing independent myographic data revealing the interaction and coordination of different muscles of the anal canal group. It employs activities of the separate muscle groups within a narrow time resolution. It involves the use of a pair of electrodes positioned on the outer surface of the insulating support for receiving myographic signals from the distal muscles of the canal and a second electrode spaced from the first electrode to receive myographic signals from the proximal muscles of the canal to provide data for the distal and proximal portions of the anal canal. U.S. Pat. No. 5,533,515 (Coller et al., 1996) relates to a sphincter myometer that includes a solid-state probe for the measurement and mapping of constriction pressure applied by the inner surface of a sphincter, or other portion of a body lumen, to the outer surface of the solid-state probe. Referring next to U.S. Pat. No. 7,485,099 (Benderev, 2009), this patent discloses a balloon-like sack holding a material for supporting the membrane to maintain a specific volume or to maintain a generally expansive state from which it is collapsible once a threshold amount of pressure is applied to the sack to enable a surgeon to position an implant, tissue, sling or graft. U.S. Patent Publication No. US 2009/0082702 A1 (Folkerts et al, 2009) relates to an electromechanical probe for stimulating the bulbospongiosus muscle and identifying the time of the stimulation so that the electrical responses from electrodes on the patient's skin can be identified for analysis. There is disclosed a screening system for measuring the bulbocavernosus reflex response when the reflex is induced from the activation of the bulbospongiosus superficial muscle of the perineum via mechanical stimulation of the clitoris or penis. The resulting reflex measurements can be used to detect abnormalities of the bulbocavernosus. In U.S. Pat. No. 7,678,064 (Kuban, 2010) apparatus is disclosed for allegedly detecting tactile sensitivity of a patient by applying pressure to the patient's body and determining the lowest amount of pressure that the patient can feel and/or the highest amount of pressure that the patient can tolerate.
U.S. Patent Publication US 2004/0054392 (Dijkman 2004) describes a probe for treating urinary and faecal incontinence, having a hollow body formed by flexible walls which transfer pressure on the walls to the interior of the probe, and a pressure sensor in the probe's interior for determining the pressure. Electrodes are located on the outer surface of the probe. The electrodes are used for electro-stimulation and measuring EMG activity. Dijkman has nothing to do with cauda equina syndrome and makes no measurement which could be used to readily indicate whether or not a person has a risk of having cauda equina syndrome, or whether any particular pressure is detected. U.S. Pat. No. 5,385,877 (Maurer et al. 1995) describes an electrode for activating pelvic reflexes for incontinence and has a flexible and anatomically-correct handle member connected to the distal end of a tubular member to properly position an electrode within a patient's rectum and prevents movement of the treated electrode. It has no relationship to the diagnosis or treatment of cauda equina syndrome. U.S. Patent Publication US 2005/0043599 (O'Mara 2005) discusses utilizing a pulse oximeter in the rectal cavity for the purpose of measuring oxygen saturation and other measurements consistent with pulse oximetry. O'Mara does not determine perianal or rectal sensation, and there is no mention that O'Mara's product can be used to determine if a patient has abnormal or absent sensation such as what would be encountered with cauda equina syndrome. None of the foregoing patents provide a system for determining cauda equina syndrome or apparatus for quickly and accurately determining if the foregoing syndrome is present or there is a risk that it is present.
“Cauda Equina Syndrome” in eMedicineHealth, Aug. 2, 2008, describes a standard diagnosis of cauda equina syndrome. Cauda Equina Syndrome has been described since at least as early as 1944, where a report in a medical journal was published: “Cauda Equina Compression Syndrome With Herniated Nucleus Pulposus, A Report of Eight Cases,” French J D, Payne J T, Ann. Surg. 1944 July; 120(1):73-87. However, no single device is known which specifically determines if a patient has cauda equina syndrome.